As wireless communication systems such as cellular telephone, satellite, and microwave communication systems become more widely deployed and continue to attract a growing number of users, there is a pressing need to accommodate a large and variable number of communication subsystems transmitting a growing volume of data with a fixed resource such as a fixed channel bandwidth accommodating a fixed data packet size. Traditional communication system designs employing a fixed resource (e.g., a fixed data rate for each user) have become challenged to provide high, but flexible, data transmission rates in view of the rapidly growing customer base.
Presently, the use of wireless networks (often referred to as “Wi-Fi” and promoted and regulated by the “Wi Fi Alliance”, an industry consortium) to provide services that are data intensive, such as laptop or portable wireless email access, internet browsing, video and music downloads, video program transmission to mobile devices, real-time gaming over the internet, voice over internet protocols for voice service (“VoIP”) and the like is often provided by wireless LAN access such as internet “hot spots” in cafes, hotels, universities and other public access areas. The compatibility and interoperability of the networks and devices in these systems is covered by various standards. Most existing wireless networks IEEE 802.11a/b/g/n standards, for example, provide wireless networking standards typically used by laptop computers, some personal data assistants (PDAs) and some portable computer devices such as palmtops, notebooks, and multimedia tablets. Advanced cellular phones with mobile internet capability may also use these interfaces. These interfaces are limited in distance and data capacity.
More recently, newer standards are being developed to enhance the range, services and bandwidths available for these internet access applications. The IEEE standard known as IEEE 802.16 covers recent developments in this area. Sometimes this standard is referred to as “Wireless MAN” but also as “WiMAX”, an acronym for “Worldwide Interoperability for Microwave Access”. The adoption and promotion of this extended wireless broadband access standard for networks is promoted by the WiMAX Forum which maintains a website at www.WiMAX.org.
The WiMAX standard was released and then amended several times to extend functionality, and the development work still continues. IEEE standard 802.16-2004, sometimes called “fixed WiMAX”, provided the broad features of the standard, adding distance and capability over 802.11 WiFi systems, but failed to address mobile devices. IEEE standard 802.16e-2005, which is sometimes referred to as “mobile WiMAX”, added support for mobile and portable devices including for example, hand-off features.
Comparing WiMAX to WiFi or Wireless LAN, the WiMAX standard provides a wireless interface to replace wired “last mile” interfaces and provide a wireless replacement or substitute for DSL or cable broadband access. The range provided by a WiMAX system may be much larger than for WiFi, for example 10 or more kilometers, and speeds may also exceed that of WiFi. Applications described by the WiMAX forum include providing portable internet connectivity, connecting WiFi hotspots with the Internet, providing metropolitan or corporate connectivity to the internet, and the aforementioned “last mile” broadband connectivity.
The user accessing WiMAX may connect to a base station that can be, for example, as small as a residential satellite TV dish, and larger base stations are also contemplated. As mobile unit support is added to the systems, laptops with PC Cards or USB dongles, cell phones, personal digital assistants (“PDAs”), internet appliances such as portable browsing tablets, MP3 players, game consoles and the like are expected to be the customer equipment that accesses the broadband connections provided by WiMAX.
Current development for WiMAX standards includes an advanced air interface standard being developed referred to as IEEE 802.16m. This standard being developed presently by an industry group known as “Task Group m” will provide extensions to the current WiMAX standards to support data rates of 100 Mbit/s for mobile applications and 1 Gbit/s for fixed applications, cellular, macro and micro cell coverage. A document titled “The Draft IEEE 802.16m System Description Document” (hereinafter the “SDD”) and numbered IEEE 802.16m-08/003r4, which is hereby incorporated by reference, describes the system that is proposed to be implemented.
One approach to increasing bandwidth in radio telecommunications is to allocate multiple carriers to carry the payloads. This has been proposed in several existing and developing standards including IMT-A and the third generation long term evolution project 3GPP-LTE. In the 802.16m SDD, the use of multiple radio frequency (“RF”) carriers to increase data bandwidth is described. Paragraph 11.6.4 provides that there will be two types of carriers a mobile station (“MS”) may receive. A carrier may be a fully configured carrier. A fully configured carrier is a carrier for which all control channels including synchronization, broadcast, multicast and unicast control signaling are configured. A partially configured carrier is defined as a carrier that is provided with essential control channel configuration to support traffic exchanges during multiple carrier operations.
From a MS point of view, these carriers can be divided into two types: primary carriers and secondary carriers. A primary carrier is a fully configured carrier and contains full physical layer and media access control (“PHY/MAC”) control information. The primary carrier is responsible for carrying all of the control information needed for proper MS operation. Each MS will have only one primary carrier. A secondary carrier is a partially configured or fully configured carrier the MS may use for traffic, but only per the allocation from the base station (“BS”) and per rules provided from the primary carrier. A partially configured supplemental or secondary carrier cannot conduct communications with a mobile station directly.
The SDD does not provide implementation details for a mobile station to efficiently access the fully configured, or primary, and partially configured, or secondary, carriers. A continuing need thus exists for methods and apparatus to efficiently perform the MS access to the primary carrier in the multiple carrier environment, such as is proposed for the advanced air interface of future 802.16 WiMAX systems.